Differential-pressure gage.



APPLICATION FILED APR. 3, 1911.

Patented Sept. 12, 1911.

Qmi/lmeooao UNITED s'rATEs PATENT OFFICE.

WILLIAM H; ams'ror, or :WATERBURY, CONNECTICUT.

. To all whom it may concern:

f Beit kno wn that I, WILLIAM H. BnIsToL, v a citizen of the United States, and a resident ofd vaterbury, in the county of New Haven and lState of Connecticut, have invented certain new and: useful Improvements in Differential-Pressure Gages, of which the following is a specification.

The-"invention relates to apparatus for Indicating. or, recording differential pressures, and more particularly to means adapted to safeguard the actuating mechanism for the indicating or recording arm against excessive differences of pressure.

'It has for its object to so protect the operating mechanism, which is usually sensitive and designed to withstand only small differences of pressure in comparison to the static pressures whose difference is to be 1ndlcat'ed or recorded, that the sub ect1ng of the gage as a whole to either of the said I ber 11 This chamber communicates throughstatic pressures, will not destroy the operat ing mechanism or in any way impair Its sensitiveness." I

The nature ofthe invention will be best understood when described in connection with the accompanying drawings, in'which Figure -1 is an elevation of a; differential pressure gage with the safeguarding apparatus attached. Fig. 2 is a fragmentary detail View. 7

Similar characters of reference designate corresponding parts throughout the several views.

Referring now to. the drawings, 7 designates a differential pressure gage of the type in which the actuating mechanism 8, for an indicating orrecording arm 9 adapted to move over a record sheet 10, is surrounded by a sealed pressure casing forming a chama' passage-way '12 withan auxiliary pressure casingforming a' chamber 13. The combined volume of the auxiliary pressure chamber 13 and theactuating mechanism 8' is made substantially equal to that of the pressure chamber 11. Thus, when the two static pressures are admitted tothe same,

approximately equal times will be required tocompletely fill the said chambers 11, and

Specification of Letters Patent. Patented Sept, 12, 1911, Application filed April 3, 1911. Serial No. 618,497.

the actuating mechanism 8 and chamber 13, with the fluid under pressure and prevent the temporary establishment of an excessive difference which would result from a lag of one of the pressures in attaining its working condition. To said auxlllary chamber 13 one of the fluids under pressure is'con-- auxiliary chamber 13, directly into the chamber 11. The actuating mechanism 8, as a rule and to provide a sufficiently sensitive gage. is not designed to withstand any great difference of pressure, such as might exist were it subjected to but one of the static pressures whose difference it is desired to indicate or record. Thatis to say, that while the actual differences of pressure to be indicated or recorded may vary from 5 or 10 lbs. for example, yet the actual static pressures producing such differences might be very considerable; and, if admitted to either side of the gage only, ,would destroythe said actuating mechanism. To obviate such contingency, it has been proposed to interlock the inlet valves 17 and 18- for the pipes 14 and 16 respectively. To this end the said valves are provided with interlocking members 19 and 20, respectively inter-4 looking with opposite sides of a member 21. The member 21 interlocks with a member 22 of a valve 23 normally maintaining open a pipe connection 24 between the two pipes 14: and 16. It will be noted that both of the s'pectively to the chamber 11 and to the actuatin'g mechanism Bandits chamber 13. As

.occur, however, that the pressure of the fluid admitted through one or the other pipes :14 or 16 would be turned off in some way at the gage; or, at some distant point, for example through the closing of a valve or 26 entirely removed from the differential' pressure gage. Or, the pressure of one such event be of no avail. 'mi g'ht, furthermore, contribute to the establishment of an excessive fluidpressure solely.

of the fluids might decrease excessively. The aforesaid interlocking mechanism would, in 20 Other causes in-the chamber 11 or in the actuating mechanism 8,: as a sudden pulsation in one of the static pressures. To provide against any =',such contingency and to positively protect the pressure gage, whether the same be pro,-

j videdwith interlocking mechanism as before described or not, and to allow of the pressure being turned on successively, the following "means have been provided. A U- tube 30 of suificient length, is partly filled with a suitable liquid such as mercury, the head of liquid beingsuited to the range of the actuating mechanism; The legs 31 and 32 of, said U-tube are preferably provided Witl1 enlargements 33 and 84 respectively,

and the tube is connected to by-pass the inlet pipes 14- and 16. Theleg3l connects with inlet pipe 14 and the leg 32 with the inlet pipe 16 beyond't'he respective valves 17 and 18 and the valve 23. a In case either of the valves 1701-18 could'by any means be opened without the other,'or if the connections to the gage-are'opened and one should be closed without the'other, the excessive pressureexisting in the one would equalize itself through the U -tube 30, the liquid therein being forced up .into the corresponding enlargement. Any otherserious disturba'nceof the static'pressures would be similarly equalized.

I claim 1. The combination with a differential pressure gage includingsuita-ble actuating mechanism adapted to be subjected .to two pressures,-- and means to admit-fluid under said pressures to the gage ;-of pressure ra a-- lating means to automatically afli'ord communication between the fluid admission means to equalize the pressures, to which the actuating mechanism is subjected, when the difi'erence'between the two, said pressures exceedsa determined amount.

2. The combination with a ,diflerential pressure gage comprising a sealed casing forming a pressure chamber, actuating mechanism within said chamber. means to admit fluid under pressure to said pressure chamber, and means to admit fluid under pressure to said actuating mechanism; of pressure regulating means communicating with both of said fluid admission means and adapted to automatically equalize the pressure between the same when the difference between the pressures existing in said fluid admission means exceeds a determined amount.

3. The combination with a dilterential pressure gage comprising a scaled casing forming a pressure chamber, actuating mechanism within said chamber, means to admit fluid under pressure to said pressure chamber, and means to admit fluid under pressure to said actuating mechanism; of a U-t'ube containing a suitable liquid, one leg of which tube communicates with one of said fluid admission means, and the other leg with the other of said fluid admission means.

4:- The combination with a differential pressure gage comprising a scaled casing forming a pressure chamber, actuating mechanism within said chamber, means to admit fluid under pressure to said pressure chamber, and means to admit fluid under pressure to said actuating mechanism; of a U-tube containing a suitable-liquid, each. leg of said tube being provided with an enlarged portion, and one leg communicating with one of said fluid admission means, and the other leg with the other said fluid admission means.

5. The combination witha differential pressure gage comprising a sealed casing forming a pressure chamber, actuating mechanism within said chamber, means to admit fluid under pressure to said pressure chamber, means -to' admit fluid under pressure to said actuating mechanism, .and a valve in each of said-fluid admission means; of pressure regulating means communicating on the discharge side of said valves with both of said fluid admission means and adapted to equallze the pressure between the same when the difference between the pres-- sures existing in said fluid admission means exceeds a determined amount.

6. The combination with a diflerential pressure gage comprising a sealed casing forming .apressure chamber, actuating mechanism within said chamber, means to admit fluid under pressure to said pressure chamber, an auxiliary casing forming a pressure chamber communicating with said actuating mechanism, the combined volume of said auxiliary pressure chamber and said actuating -mechanism being substantially equal to the'volume of said sealed pressure chamber, and means to admit fluid under pressure to said auxiliarypressure chain her; of pressure regulating means communi- NeW-Y0rk and State of New York this 30 eating with both of said fluid admission day of March A. D. 1911.

means and adapted to equalize the pressure I between the same when the difference bep WILLIAM S 5 tween the pressure existing in said fluid ad- \Vitnesses mission means exceeds a determined amount. LAURA E; SMITH,

Signed at New 'York, in the county of 'FREDK. F. ScHUn'rz. 

